


Staking His Claim

by cloud_dcst (greatcloudninja)



Series: TKS TsukaSen Week [6]
Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: Alternate Universe - High School, Alternate Universe - Modern Setting, Creampie, Date Rape Drug/Roofies, Dead Dove: Do Not Eat, Discord: The Kingdom of Shipping (Dr. STONE), Drugged Sex, Explicit Sexual Content, Jealous Shishiou Tsukasa, Jealousy, Love Bites, M/M, Non-Consensual Somnophilia, Rape, Soft Yandere Shishiou Tsukasa, TKS TsukaSen Week - Modern AU, TKS TsukaSen Week - School Days, TKSevents, Tsukasen, Underage Rape/Non-con, sex at school, tkstsukasenweekjan2021, tsusen, 司千
Language: English
Status: Completed
Published: 2021-01-30
Updated: 2021-01-30
Packaged: 2021-03-16 00:48:18
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 2,215
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29073576
Author URL: https://archiveofourown.org/users/greatcloudninja/pseuds/cloud_dcst
Summary: When Tsukasa went to his classroom to find Senku, Taiju happily spilled the beans about how a girl had asked Senku to meet him behind the storage shed by the school’s soccer field.Oh.Tsukasa’s breath caught in his throat.Of course.Of course other people were going to see how cute Senku was. Some people found his dry intellect prickly, but others—others like Tsukasa—could see past it to his sweet, kind heart and his wicked sense of humor.Tsukasa fled the room before Taiju could even finish his explanation.Senku… is mine. No one else’s.It was the only thing that Tsukasa’s mind could focus on.If he won’t turn down this girl… I’ll just have to make sure he knows he belongs to me.MIND THE TAGS.
Relationships: Ishigami Senkuu/Shishiou Tsukasa
Series: TKS TsukaSen Week [6]
Series URL: https://archiveofourown.org/series/2123469
Comments: 4
Kudos: 94
Collections: TsukaSen Week January 2021





	Staking His Claim

**Author's Note:**

> MIND THE TAGS. DO NOT READ IF YOU ARE NOT PREPARED TO SEE THIS CONTENT. YOU HAVE BEEN WARNED.
> 
> This is my entry for Day 6 of [TKS TsukaSen Week](https://twitter.com/tksDCSTevents)! I used the prompts "Modern AU" and "School Days" for this one!

Shishiou Tsukasa had a secret.

He was dating first year Ishigami Senku, the whiz kid of the Science club. They’d known each other since they were young, when Tsukasa stopped some bullies who were trying to break some of Senku’s science equipment. His friend Taiju was doing his best to block the bigger kids from attacking, but he wasn’t fighting back—so Tsukasa felt obligated to step in and drive the boys off. It had sparked a fast friendship, lasting all the way through middle school and into high school.

And now Senku and Taiju were finally students at the same high school Tsukasa attended as a third year student. But even Taiju didn’t know about the sweet kisses that Tsukasa stole from Senku’s lips as the two of them ate lunch together on the school’s roof. It was one of the few times they got to spend together during the day, since their classes were in completely different wings of the school. But they couldn’t eat lunch together _every_ day, or it would get suspicious; so they usually picked one day a week to sneak away and see each other for their precious few minutes of privacy.

Unfortunately, Senku was running late today. When Tsukasa went to his classroom to find him, Taiju happily spilled the beans about how a girl had asked Senku to meet him behind the storage shed by the school’s soccer field. “I think she’s a second year? She’s not in the science club, but she said she had to ask Senku an important question and had something to give him!”

 _Oh._ Tsukasa’s breath caught in his throat. _Of course._ Of course other people were going to see how cute Senku was. Some people found his dry intellect prickly, but others— _others like Tsukasa_ —could see past it to his sweet, kind heart and his wicked sense of humor.

Tsukasa fled the room before Taiju could even finish his explanation. He didn’t stop running until he’d made it around to the back of the school.

“Please accept this!” Peering around the corner, Tsukasa caught a glimpse of a spill of silky blonde hair. Standing in front of Senku was a petite girl holding out a pale pink envelope, sealed with a heart-shaped sticker. “It’s very important to me, so please, take it!” 

Tsukasa’s heart pounded; blood rushed through his ears, muffling any other sounds as he watched Senku’s hand reach out and take the envelope. Senku might have been talking, but Tsukasa couldn’t make anything out. He had to—he couldn’t be seen here. There was no telling what might happen, or _what he might do,_ if this girl spotted him _._

 _Senku… is mine. No one else’s._ It was the only thing that Tsukasa’s mind could focus on. _If he won’t turn down this girl… I’ll just have to make sure he knows he belongs to me._

Later that afternoon, after classes and club activities had let out for the day, Tsukasa sent Senku a text.

_I missed you on the roof today. Rain check for tomorrow?_

The reply he got was nearly instantaneous. _Yes. Had an unfortunate interruption today, but tomorrow sounds great. Looking forward to it 10B%._

Tsukasa’s lips curled into a soft, fond expression as he looked down at his phone. He loved Senku’s cute little mannerisms so much, like his penchant for the phrase “ten billion percent.” It was just so… _Senku._ Tsukasa wanted nothing more than to take his lover and tuck him away, to keep him safe from the world and everyone in it. And if given half a chance… he absolutely would.

The next day, Tsukasa was waiting for Senku up on the roof a little early. He’d packed lunch for both of them, making sure all of Senku’s favorites were in the bento box. Tsukasa had even gone so far as to pack a blanket for them to sit on.

“You really went all out today, didn’t you?” Senku mused as he stepped through the door onto the roof. “All this because we didn’t get to have lunch together yesterday?”

Tsukasa gave a one-shouldered shrug. “I missed you, so I wanted to make it special for you.” He was already opening up the top portion of the lunch box, having procured what looked like two pairs of disposable bamboo chopsticks for them to use. He handed over a bottle of tea, as well.

Senku sat down next to Tsukasa on the blanket, leaning against his shoulder and sipping at the tea. “You’re amazing. I’m starving.”

“Don’t worry. I brought plenty.” Before handing over the food, though, Tsukasa leaned down and wrapped his hand around the back of Senku’s neck. “But first… you don’t mind if I take something from you… do you, Senku?” 

He could feel the way the younger boy’s breath stuttered as Tsukasa captured his lips in a deep, bruising kiss. The knowledge that Tsukasa had been the first—and was the _only—_ to kiss Senku like this sent a deep pang of arousal through his body.

It was time for Tsukasa to show Senku the truth about who he belonged to. He didn’t let up on the kiss, slowly lowering Senku backwards until the boy was pinned to the blanket. “Senku, you taste so good,” Tsukasa whispered.

“Hnn… Tsukasa… wh-wha…?” Senku’s gaze was already growing hazy. Tsukasa had only seen this expression on Senku’s face once before; it had been the first time he’d ever touched Senku _there,_ one night when Tsukasa had slept over at Senku’s place. Tsukasa would never forget the cute flush that had bloomed as Senku’s sweet lips had cried out and his spend had covered Tsukasa’s fist.

But today called for more. Tsukasa couldn’t just make Senku feel good, no; Tsukasa needed to _stake his claim._

Hovering over Senku, Tsukasa’s hands made quick work of the boy’s lab coat and tie. The shirt followed moments later, leaving Senku in just his pants until they, too, slipped away. Tsukasa laid kisses over his cheeks, lips, and jaw as he worked the clothing off of his lover’s body. “You’re so beautiful,” Tsukasa whispered. “Is the tea helping to relax you? I hope you don’t mind I added a little something extra to it. Not much; you’ll just be a little sleepy for a while, but after we finish our date I’ll take you down to the infirmary to rest.”

“Tsu… kasa…” Senku’s voice was so quiet, a far cry from his usual drawl, that Tsukasa couldn’t help cooing over how cute he was. His brow furrowed like he wanted to say something, but apparently he couldn’t get the words out.

Tsukasa pressed a finger to his lips, shushing him gently. “It’s alright, Senku. Don’t worry. I’m here. You’re mine and no one else will ever have you… I’ll keep you safe and make sure everyone knows you belong to me.”

As he spoke, his free hand reached for the bottle of lube he’d make sure to pack alongside the lunchbox. He would never forgive himself if he hurt Senku their first time! Peeling back Senku’s underwear, he slicked the fingers of one hand before spreading his little lover’s ass cheeks with the other and taking a peek. 

_Oh,_ Senku’s hole was beautiful. A sweet, pink void, untouched by anyone before now… Tsukasa’s mouth watered at the thought of tasting it in the future. But at that moment, he had more important things to do. He slathered lube over the winking hole, then carefully worked his first finger inside.

Stretching Senku out was a slow process, but the fact that he didn’t resist helped so much. The fast-acting sleeping pill Tsukasa had put into the tea was doing its job to help Senku relax; his hole more easily accepted the intrusion as Tsukasa stretched him around a second finger, then a third. “You’re doing so well for me, Senku,” Tsukasa mumbled. He reached up with his clean hand and pet at Senku’s hair absently. “My boyfriend is so handsome and beautiful… I’m so lucky… I love you, Senku, never forget that. You’re mine, right? You want to be with me, don’t you? That’s why I’m doing this, so that girl and everyone else will know who you belong to. No one will mess with you again or try to come between us, I promise.”

Leaning over Senku’s body, Tsukasa dropped a kiss to the slack, pink lips of his beloved boyfriend. “I think you’re ready now. I’m going to fuck you; I’ll make you feel so good, you won’t know what to do with yourself.” With that, he slid his fingers out of Senku’s hole and shoved his own pants down enough to release his trapped erection. He’d been achingly hard the entire time he’d been stretching Senku, but making sure his lover was ready for him was far more important than his own relief. He quickly slicked his length for good measure with what was left of the lube on his hand.

Finally, though, it was time. Tsukasa held himself steady with one hand and wrapped the other around Senku’s hip, lining himself up and pushing inside… and _oh,_ it felt so good! Senku was hot, tight and velvety-soft inside around his cock. The texture was unlike anything Tsukasa had ever felt before—completely different from his own hand, even with the lube. Tsukasa pushed inside until his hips were flush with Senku’s, then paused. He needed a moment, or he might completely humiliate himself.

After a few deep breaths to get himself under control, Tsukasa began to move. He used one hand to lift Senku by the hips and get a better angle for himself to fuck into his lover more easily. “So good… feels amazing… you’re wonderful, Senku, I love you so much…” The words spilled from Tsukasa’s lips. His other hand ranged Senku’s body—tweaking his nipples, stroking his hard cock. Every touch elicited a soft sound from the boy’s plump, slack lips. Knowing Senku was feeling good too only made Tsukasa even more eager. “You like this, right? You feel good? I knew you would enjoy it, after all, we’re _made for each other…”_

Tsukasa knew he didn’t have long. Their lunch dates were always terribly short; far too little time for him to be fully satisfied. So he sped up his movements, snapping his hips harder and faster until he could feel the burn of his impending ejaculation. “It’s going to be messy, I’m sorry,” he murmured into Senku’s ear. “I hope you won’t mind.” With that, he moved his head down to seal his lips around the tendon in Senku’s neck, right where it led up to his jaw. Everyone would be able to see the messy bruise he left there—and everyone would know, _Senku was off-limits._

The mental image of that second year girl seeing Tsukasa’s love bite on Senku’s milky skin was enough to push him over the edge. He groaned as his body spasmed, spurt after spurt of thick cum filling Senku’s hole. Distantly, he was aware of the feeling of Senku’s cock twitching in his hand. He couldn’t help smiling inwardly. Wasn’t that just another perfect example of their compatibility, the fact that they came together?

Tsukasa carefully lowered Senku down onto the blanket once more. Once he’d withdrawn from Senku’s body, he dug around in his backpack until he found the packet of wet wipes he’d brought. He cleaned up the lube and cum from his hands and wiped his cock clean, then he gave Senku’s belly a cursory swipe to collect most of the cum that had spilled over from his orgasm. Once they were both cleaned up to his satisfaction, he carefully re-dressed Senku and ran a hand through his hair to adjust his spiky cowlicks. “There. Good as new… well, almost.” The love bite he’d left on Senku’s neck was already purpling, making Tsukasa grin. He couldn’t help himself—he dropped another kiss to Senku’s lips before biting down on the other side of his neck for good measure. If one mark would keep the annoying pests away, two would be even better, right…?

They only had a few minutes left in their lunch break, so Tsukasa hurried to shovel food into his mouth and pack up their belongings. When the roof was as clean as it had been upon his arrival, Tsukasa carefully scooped Senku into his arms. There was a flat, thick something in his lab coat pocket that Tsukasa hadn’t noticed while undressing him earlier… Senku wouldn’t mind if Tsukasa took a peek, right? He reached into the pocket and withdrew a pale pink envelope.

The love letter from yesterday. 

But it didn’t have Senku’s name on it. _Shishiou Tsukasa._ She wasn’t confessing to Senku at all—she was asking Senku to give this to _him…_

Tsukasa could only pull Senku closer. It didn’t matter. If not this girl, _someone_ was going to get the wrong idea and try to take his lover away. Tsukasa was just heading things off at the pass. He ripped the letter in half and shoved it into his pocket before navigating to the door heading off the roof. 

Senku needed to get some rest. He’d had a hard lunch; he deserved it.

**Author's Note:**

> Feel free to join the Dr. Stone shipping server! All ships are welcome!  
> We have lots of events scheduled, RP our fave ships, share headcanons, etc!  
> [Click here to join us!](https://discord.gg/RGy78Kj)


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